Rock drill



Patented June 30, 1936 UNITED STATES PATENT OFFICE ROCK DRILL Application August 8, 1934, Serial No. 738,921

1 Claim.

This invention relates to rock drills, and more particularly to pressure fluid actuated rock drills of the percussive type for drilling holes upwardly. Such drills are known in the art as stopers.

In this class of drills it is not customary to provide means for cleansing the hole being drilled by a jet of pressure fluid for the reason that the hole will normally be cleansed by gravity. Water is sometimes forced into the drill hole, but this is more for the purpose of diminishing the quantity of free dust than for cleansing. Whether water is employed or not, however, dust, grit, and rock particles falling from the hole, often drop into the front end of the rock drill and work their way into the drill mechanism where they have a pronounced abrasive action which greatly shortens the effective life of the drill.

It is an object of my invention to provide means for conducting a continuous flow of pressure fluid to a point near the front end of the drill and there releasing it in such a way as to sweep away all dust, grit and the like which might enter the front end of the drill, before it can find its way into places where its presence will cause damage.

The invention maybe best understood by reference to the accompanying drawing in which Fig. 1 is a longitudinal section of a rock drill embodying the invention;

Fig. 2 is a cross section taken on. the line 22 looking in the direction of the arrows; and

Fig. 3 is a greatly enlarged view of a part of Fig. 1 to more clearly illustrate the operation of the invention.

Referring to the drawing a rock drill IQ of conventional type has a cylinder l2, in which a piston I4 is adapted to reciprocate. The cylinder is closed by front and back cylinder washers l6 and I8. A throttle valve 20 located in a back head 22 is provided to control the admission of pressure fluid to the drill.

Mounted in a valve chamber between the back head 22 and the back cylinder washer i8 is a distributor valve 24 of well known type controlling the admission of pressure fluid to the rear of the cylinder through inlet 26 and to the front of the cylinder through the inlet bore 28. Conventional exhaust ports 30 are provided in the cylinder.

The front cylinder washer I6 is provided with a bore to receive an impact element or anvil block 32. A front head 34 is here shown with a bore, the front portion of which is hexagonal to receive a drill steel 36, the rearward portion of the bore being in the form of an enlarged cavity into which the adjacent ends of the drill steel and anvil block extend. The front head may be clamped to the cylinder in any convenient manner and serves to hold the front cylinder washer I6, the fore part of which it encircles, in place. This construction is all well known in the art and no detailed description is necessary.

A pressure fluid passage is provided from the throttle valve to the front head in the vicinity of the front end of the front cylinder washer. The throttle valve 20 may be provided with a secondary bore 2| and a slot 28 which upon rotation of the valve may be brought into and out of registry with a passageway 25 formed by a series of connecting bores in the back head, back cylinder washer, cylinder, front cylinder washer, and front head. It will be understood that when the throttle valve is open the passageway 25 is filled with pressure fluid. at full line pressure.

At the front end of passageway 25, at the rear of front head 34, an outlet is provided to an annular groove 38 cut on the inside of the bore of the front head. The front part of the front cylinder washer It is encircled by this grooved portion of the front head 34 and the parts have a working fit. In Fig. 3 the clearance between these parts is greatly exaggerated for illustrative purposes.

Pressure fluid entering the groove 38 escapes through the clearance space between the front cylinder washer and the front head into the interior of the front head, whence it flows to atmosphere past the working implement 36, or by means of a port 40 which may be provided. In flowing from the annular groove 38 the fluid will take the form of a high velocity annulus which will eifectively oppose the entrance of any dust or grit into the drill mechanism.

Having thus described the invention and the means whereby I have accomplished the objects thereof, I do not desire to be limited to the specific form disclosed, for it is clear that many modifications may be made without departing from the spirit of the invention.

I claim:

In a pressure fluid actuated drill, a front head having a cavity and an annular groove in the cavity, an anvil block extending into the cavity, a passage for supplying pressure fluid to the groove, and a front cylinder washer to guide the anvil block and having a portion overlying the annual groove and cooperating with the wall of the cavity to define an annular outlet opening for the groove around the anvil block whereby an annulus of pressure fluid surrounding the anvil block is introduced into the cavity to prevent the lodgement of foreign matter on the anvil block.

WILLIAM A. SMITH, SR. 

